Vehicle movement dynamics control systems are electronically controlled driving assistance systems for motor vehicles, wherein the driving behavior of the vehicle is stabilized by control interventions in the drive and/or the brakes. For example, the veering off of a vehicle can be counteracted by targeted braking of individual wheels. Vehicle movement dynamics control systems can be configured, for example, as anti-lock brake systems or traction control systems and are often combined with an electronic brake system, in particular in utility vehicles.
Vehicle movement dynamics control systems which are intended to prevent rollover of the vehicle while taking into account a tilting limit, are referred to as “Roll Stability Control” (RSC). The RSC function is often implemented as an additional function of a vehicle movement dynamics control system.
Roll stability systems can effectively prevent utility vehicles from tilting by selective control interventions if the tilting limit can be reliably obtained. Tilting limit is understood here to mean the maximum lateral acceleration above which tilting of the vehicle is possible. The tilting limit is determined in addition to vehicle-specific parameters, in particular of the height of the center of gravity. In particular in utility vehicles with a high center of gravity, a low tilting limit is given when the load is unfavorable.
EP 1 592 592 B1 discloses such an RSC vehicle movement dynamics control system. In order to increase the driving stability of a utility vehicle, instability of the vehicle is counteracted by control interventions into a control system which activates the drive and/or the brakes of the vehicle, wherein in the known method the control intervention is intended to take place as a function of a ratio between the height of the center of gravity of the vehicle and a spring constant of the vehicle suspension system.
In tractor-trailer combinations, that is to say combinations of one tractor with at least one trailer, different mass distributions between the tractor and the trailers are actually not taken into account with the conventional RSC control systems. The tilting limits can vary in different vehicles and can differ from one another significantly as a result of different cargos of individual vehicles. If one of the vehicles which are connected together is heavily loaded to a critical extent in terms of tilting, while another vehicle is traveling empty and there is therefore a low risk of tilting, tilting may occur when cornering. In order to avoid this, the vehicle movement dynamics control system is to be configured with a corresponding compromise between protection against tilting and drivability. However, during journeys with uniform distribution of the cargo in the vehicles of the tractor-trailer combination this results frequently in control interventions which are not necessary for the driving stability and are experienced as unpleasant by the driver of the vehicle.
EP 0 737 608 B1 relates to a method for determining the ratio of the mass of a road train and the mass of the tractor, wherein a braking force distribution between the vehicle axles is determined at the tractor. If the vehicle has an air suspension system, the axle load and therefore, in turn, the cargo can be inferred from the necessary bellows pressure, as result of which the total mass of the vehicle is to be determined. The masses of the other vehicles of the road train are obtained by multiplying the mass of the one vehicle with the obtained ratios between the masses.